Any Max- name could be shortened to Mack, it would make a change to Max. Also MacKenzie, McKinley, Macson, Mackley? My surname starts with Mc so using a Mac/Mc name as a firts name would be offlimits unless I got married unfortunately because I really like some.

I love Mack for the song "Mack the Knife" and so I could see myself considering other names like Macheath (the character it's supposedly based on), Berthold (the writer of the Three PennyOpera), or Kurt (the song writer) with nn's Mack. They aren't as intuitive, heck the last two are really out there but you know, whatever works for you. Maybe you like the name for a character played in a movie by a particular star whose name you like as well... I'm sure you'll find a good way to make Mac/k work for you.